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The iNARTE Informer – October 2012

All iNARTE administration has now been successfully transferred to the Milwaukee offices of RABQSA International. Even our legendary telephone number, 1-800-89-NARTE, now rings directly into the RABQSA office. So now there are the following phone numbers that are available to call for information about iNARTE certification or FCC Licensensure:

1-800-89-NARTE
1-888-722-2440
1-414-272-3837

The iNARTE web site remains intact and all information and downloads are available still at www.narte.org. However, we encourage you to also visit www.rabqsa.com, where you will find a quick link to iNARTE on that home page in the “certify me” box.

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VSWR and its Effects on Power Amplifiers

Voltage Standing Wave Ratio results from an impedance mismatch between a source (an amplifier) and a load (test application). This mismatch can influence the performance of the source.

LOOKING BACK ON PITTSBURGH

Pittsburgh was a pleasant surprise. In my 50 years or so of business travel I had never had the occasion to visit the city of Pittsburgh, but in my mind I had an image of a dark and somber place covered in a film of industrial grime. Not so! Pittsburgh was welcoming, bright and sunny, with pleasant walks to a variety of most enjoyable restaurants, bars and sidewalk cafes. Oh, and so many yellow bridges I gave up counting.

Maybe the only issue was the fact that the convention center seemed to be back to front as far as getting there from the hotel. Had we arrived by boat it would probably have made sense.

The EMC Symposium itself was most enjoyable and we congratulate the organizers on a job very well done. Long Beach in 2011 was a tough act to follow, but Pittsburgh did not disappoint. We were encouraged by the number of visitors to our booth and the greater than expected number of candidates attending our certification examination day on the Friday.

I had not scanned our data base to find the number of iNARTE certificate holders and pending applicant there were in the Pittsburg area before arriving there, so you can imagine how surprising it was to find one of our very first applicants still struggling with those darned 10 new questions that we ask for.

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This image has caused us to think about how we might restructure that 10 question requirement to make it easier for applicants and more beneficial for iNARTE.

Oh those darn’ new questions

WHAT ABOUT THOSE DARN’ QUESTIONS

The original intent behind asking applicants to write 10 new questions as part of the certification requirement was twofold; first we thought it would give our review committee further insight into the breadth of knowledge of an applicant, and secondly it would give us a wealth of new material to maintain the standard and currency of our question pools. In both regards it has fallen short of our expectations.

Some applicants have taken this requirement very seriously and a number of really good questions are received. However, far too many applicant questions are simply copied from examples given at the end of chapters in more popular reference books and manuals. Many others are extracts from common regulatory standards, or perhaps worse still are taken from highly specialized or obscure standards that most candidates would never think of bringing to the examination room.

From a typical batch of 100 applicant questions, we find about 50 that are essentially duplications of existing questions, another 20 that are not challenging enough to demonstrate competence, 20 that are incorrectly presented or simply incorrect, and maybe 10 that are worthy of keeping. The net result is that over time the quality of our question pools has been difficult to maintain. It is time to take a different approach:

THE FUTURE PLANS FOR APPLICANT QUESTIONS

Now that iNARTE is part of the much larger RABQSA organization, we have a professional psychometrics department available to us. This additional resource will enable us to better understand the science of good question writing and good examination structuring in order to achieve the results that both we and our applicants desire.

By October 1st this year we will have changed the applicant question requirements. Instead of asking for 10 questions we will ask for just THREE (3) questions. However, each applicant will be required to watch a short presentation on good question writing techniques that will be available for viewing on our web site. We will also be asking applicants to write questions for us in categories that we will define. With this change of requirement we will be more demanding and critical of question quality. We will be expecting to see the following important criteria observed.

Good Questions

Help determine which examinees have the subject knowledge
Have alternate, but incorrect, answers that are within the knowledge domain
Include subjects that are meaningful to the scope of the test
Are written clearly and can be understood the first time they are read

Bad Questions

Trick examinees into choosing an incorrect option, even when they know the answer
Measure knowledge domains outside the intended subject
Include slang terms or are not sensitive to the diversity of the examinees
Remind examinees that they are taking a test

The web site presentation will help applicants achieve these objectives and will provide us with a much improved number of challenging and suitable questions to maintain our pool quality.

Above all, remember to write questions that are applicable to the certificate for which you are applying. An iNARTE certified Engineer in our classic EMC, ESD or Product Safety program should have 9 years of education and work experience. Consequently that person should be expected to answer almost every good question that requires remembering and understanding the question subject matter. That person should also be able to answer most questions that require the knowledge to analyze and apply what they remember and understand. Then perhaps just a few will be able to answer questions that require a higher level of evaluation and creativity to find the right answer.

An examination that is intended to determine engineers that have achieved a competency level to be expected after nine years of experience will be populated with many more of the questions that require the ability to analyze and apply principles, rather than simply remember them.

 

QUESTION OF THE MONTH

Last month we asked:

 

A signal with amplitude spectrum shown below

is passed through an ideal lowpass filter with unity gain and 1 kHz bandwidth. The percentage of the input energy appearing at the filter output is ______ .

A) 50%
B) 66.7%
C) 80%
D) 90%

The answer is (C) 80%

The input energy is proportional to 1/4 + 1/4 + 2 = 2 1/2 = 5/2 volts2 • sec2.

The output energy is proportional to 2 = 4/2 volts2 • sec2.

The percentage is (4/2)/(5/2) × 100 = 4/5 × 100 = 80%.

 

This month’s question is:

Let H and E be the Phasors corresponding to a plane wave at some point in space, and H* and E* are the complex conjugates of H and E. How would you calculate the average power density in this plane wave?

A) Real (E × H*)
B) Real (E × H*)/2
C) Real (E × E*).
D) Real (H × H*).
E) Real (E × E*)/2Z, (where Z is the impedance of the medium).

 

author_lawrence-brian Brian Lawrence
began his career in electromagnetics at Plessey Research Labs, designing ”Stealth” materials for the British armed services. In 1973 he moved to the USA and established a new manufacturing plant for Plessey to provide these materials to the US Navy. In 1980 he joined the Rayproof organization to develop an Anechoic Chamber product line. As a result of acquisitions Rayproof merged into Lindgren RF Enclosures and later into ETS-Lindgren. Following a career of more than 40 years in the EMC field, Brian retired as Managing Director of ETS-Lindgren UK in 2006. Later that year he assumed the position of Executive Director for the National Association of Radio and Telecommunications Engineers. NARTE. Now renamed iNARTE, the Association has expanded its operations and in 2012 merged with RABQSA International, a subsidiary of the American Society for Quality, ASQ. Brian remains associated with RABQSA through this merger process.

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